Urbanization has produced an increase in impervious surfaces which is reducing the amount of stormwater infiltration and rapidly increasing the surface runoff. Urban stormwater carries a variety of pollutants from activities on residential, commercial, and industrial land and also from different land covers. While consideration has been paid in recent years to urban point source pollution control through the establishment of wastewater treatment plants in many developing countries, no considerable planning nor any serious measures have been taken to control urban non-point source pollution (urban stormwater runoff). But, urban non-point source pollutants are a serious problem for receiving water bodies. Increases in urbanization have resulted in the degradation of water quality specifically from urban stormwater. The study was performed in the Bahir Dar City located in the northwest part of Addis Ababa. Bahir Dar city is one of a rapidly growing City with the increasing of impervious surface and urban runoff where pollutants are generating to the Lake Tana. From the City, runoff with pollutants is discharging to the receiving water body, Lake Tana mainly through manmade drainage and Zengo River. The primary objective of the thesis is to quantify pollutants load from untreated urban runoff. Untreated urban runoff samples were collected from 6 rainfall events from 6 sampling sites (St1.St2, St3, St4, St5, and St6) and a total of 10 water quality parameters during the rainy season which analyzed in the laboratory. The study was conducted from June 2019 to August 2019. Pollutants were estimated using a simple method as the product of estimated runoff volume and pollutant concentration. The result of water quality parameters in study periods were ranged;-Temperature(18.98 to 19.39),PH (6.58 to 7.14),EC (130.17 to 520.67μs/cm), DO (4.15 to 5.62mg/l),BOD5 (21.33 to 72.25 mg/l),TDS (95.75 to 357.20 mg/l),TSS (164.17 to 232.25mg/l),TN (13.62 to 36.99mg/l),TP (0.34 to 3.85mg/l),and TC (33 to 203). Temperature, PH, EC, TDS, and TC were under the limit of standards, whereas BOD5, DO, TSS, TP and TN were above the standards. On the other hand the total annual pollutants load estimated was 3,482,299.4 kg per year which were measured as physicochemical, and 5,746.5 billion bacteria per year generated from study area. Generally, Stormwater runoff generated from Bahir Dar needs treatment before it joins the Lake, and urban catchment treatment along the shore has to be done to safeguard the lake.